The present invention relates to a method of obtaining the yawing velocity .omega. and/or the transverse velocity v.sub.y of a vehicle, or a vehicle value that is a function of the yawing velocity and/or the transverse velocity of the vehicle, in order to control a system of the vehicle.
A robust model servo-control based on the state variables of transverse and yawing velocity may be considered as a concept for the provision of a controlled rear-wheel drive system, see for example, German Unexamined Published Patent Application DE-OS 4,030,846.
Although there exist notechnical limits for measuring the yawing velocity with the aid of a stabilizing gyro, a rate sensor or a fiberoptic gyro, and measuring the transverse velocity with the use of optical correlation methods, the use of appropriate sensors and the information processing systems required for the measuring signals go beyond the economical framework of, for example, a controlled rear-wheel drive system.
One possibility for determining the difficultly measurable state values is the use of a state estimator such as a "Kalman filter". However, a vehicle is characterized by great non-linearities and variable parameters, e.g. position of center of gravity, lateral rigidities of the tires, vehicle speed, etc. Consequently, a corresponding non-linear Kalman filter quickly exceeds the computing capabilities of a vehicle computer.